Power-driven reciprocating hand tool



UST/'Lim pril H4, i935. W H, DEAN POWER DRIVEN RECIPROCATING HANDv rFOOLFiled NOV. 20, 1954 2 Sheets-Sheet l Jn/vm WILLIAM HENRYDEAN,

pyi M, ma, w. H. DEAN 03am POWER DRT-VEN RECIPROCATING HAND TOOL FiledNov. 2o, 1954 `2 sheets-sheet 2 FIGA( i n I JWM/wv WILLIAM HENRY DEAN,

Patented Apr. 14, 1936 iJiTED STATES PATENT OFFICE POWER-DRIVENRECIPRQCATING- HAND TOOL William Henry Dean, Darlington, EnglandApplication November 20, 1934, serial, No.. 753,895 In Great BritainDecember 1,1933- Claims.

This invention relates to improvements in power-driven` reciprocatinghand tools, and has for its primary object the provision of apower-driven i the tool whereby it can be guided through the workwithout risk of injury to the operator.

Other objects and certain advantages of the invention will becomeapparent from the follow.

ing description when taken in conjunction with the accompanyingdrawings, the invention consisting in the novel features ofco-nstruction, combination and arrangement of parts hereinafter fullydescribed and pointed out in the appended claims.

The drawings herewith illustrate, by way of example, twopower-reciprocated hand tools in accordance with my invention. In thedrawings,

Figure 1 is a perspective view of a two-handled saw reciprocated byllexible cables and mechanism driven by an electric motor;

Figure 2 is an elevation of the casing containing the reciprocatingmechanism, partly in section;

Figure 3 is a central section at right angles to Figure 2; and

Figure 4 is a central longitudinal section of the two handles showingthe connection of the ends of the saw blade to the flexible cables.

Figures 5 and 6 are an elevation and a plan respectively of an electricmotor fitted with mechanism for reciprocating a single-handled saw;

Figure 'l is a central longitudinal section of the handle of thesingle-handled saw;

Figure 8 is a plan of said handle, partly in section;

Figure 9 is an elevation looking onv the lefthand end of the handle; and

Figure 10 is as section on the line Ill-l0 in- Figure 'l Similarreference letters are used in both constructions to indicate similarparts.

Referring to the said drawings, inthe example illustrated in Figs. 1 tofl, the ends of a short saw blade w are received in clamps comprisingsplit bolts b tted with holdingnuts bi1 rigdlymounted onfthe outerendsof piston-like blocks c in ai. pairA of cylindrical handles d, said,blocks` being normallyY pressed towards the, forward ends ofv said'-handles by spiral springs e within the handles and adapted to beretracted against said springs 5 by flexible steelcables f attachedat qto thegjlnfner endsof' said blocks. The other ends; of the;4 operatingcables are-oppositely attached by spherical-headedv nipples h to collarsi on an eccentric pin`r lc projecting from the face of a flywheel 10lboss m screwed' onto the; end oftheshaft 11, oran; electric motor o andlockedthereongby. asetscrew m1. The rim m2 of the flywheel` isofaluminium. shrunk onto the boss m. 'I'he'` cablesf are; en.

closed in flexible nonfreciprocatlng sheaths p the endsl ofv which abut,against, adjustable stops T1 at the rear ends of -thehandles dv andiixedstops` r2 at the ends of a casing q` enclosing the reciprocatingmechanismV and' supported bybracketsv oi1 from the housing of the motoro. v

The motor-driven mechanism in thev casing qy rapidly reciprocates thesaw blade-,a between thev handles elv whichv areA held by the operatorand used to apply the blade to the work and guide it therethrough. 251

To minimize friction, ample lubrication of the; flexible drive isnecessary,and.-I utilize the casing q of the reciprocating mechanism as.a reservoir for oil, said casing being normally closed; by a cover q1.The sheathed operating cables fare enclosed4 in flexibletubes?` attachedat onei endi of the sockets r4 ofthe xed stops 1'2 which form oil-tightjoints and are, provided withaperturesy r3 (Fig. 2)k through which thecablesf enter the interior of the casing. The other ends of the tubes 'rare attachedv to the stops r1 at the rear ends ofthe handles, d. Oil,supplied to th-e cas,- ing q is fed therefrom through the apertures r3into the sheaths paround the cables f and percolates through said:sheaths into the tubes r 40 thusensuringthat the tubes 'r arecontinuously supplied withoil and that the cables f, run in oilf intheir sheaths. p. Moreover the oil travels` through the flexible driveinto the handles andv lubricates the blocks c therein. The. oil,.whichis introduced into` the casing q. through an aperture q2 when the screwplug q3therein isiremoved, is preferably of medium and clinging,v bodyand of a heat-resisting nature. The aperture c4 in the bottom of thecasing. qallows-.the oil to ,bedrained from the casing, when desired,byremoving the screw plug qw5. The sheaths p comprise closelywound steelspirals ther turns of which ope-n-M slightly when the cables andisheaths. are bent. The passage offoil' through thegsheaths is thus 55.

facilitated Where the cables are bent, which coincides with thepositions Where the friction is greatest. A further advantage of thesurrounding flexible tubes 1 is that they prevent the sheaths p andcables f being bent too acutely. The flexible drive may be of anysuitable length.

The ywheel m, m2 acts as an oil impeller and throws oil towards the endsof the casing q which ensures the entrance of the oil into the flexibledrives f, p, 1*. The casing q is maintained fully charged with oil. u

With adequate lubrication, little or no vibration is imparted to thehandles, and accurate cuts can be readily and rapidly made by means ofthe reciprocating blade.

The handles each comprise a base portion d closed at its rear end toform an abutment against which the spring e bears. The ends of the sawa; and the ends of the operating cables ,f are rigidly clamped to theblocks c in the two handles, the cables passing through the centres ofthe Vsprings e and out through the stops r1 which are screwed intothreaded apertures provided in the rear ends of 4said handles. a

The Vbase portion of the right-hand handle has at its forward end areduced portion d1 provided with an axial slot d2 to receive aprojection s` on the block c within said handle. Over the reducedforward portion d1 is loosely slipped a sleeve t held in position by aring u screwed onto the forward end of said reduced portion, said sleeveserving to cover the slot d2. 'I'he block c in the left-hand handle isnot provided with a projection s and is free to rotate therein. Thisarrangement allows the operator to control the cutting angle of the sawby the right hand alone by turning the right-hand handle and so varyingthe cutting angle of the blade.

lThe base portion dof the left-hand handle is fitted with a lining d5which is attached to said cylinder by a screw d4 engaging a slot d6 insaid lining which allows the latter to be slidden into the cylinder touncover the block c when required. 'I'he rear end of the slot d6 has aright-angled extension so that, by turning the lining slightly, it canbe locked against rearward movement. Over said lining is slipped a tubed'7 which is externally threaded and is held between a ring da screwedon the forward end of the lining d5 and the forward end of the baseportion d, said tube being fitted with an internally-threaded sleeve t1terminating in a cone t2 which acts as a guard while permitting the lineof cut to be watched through the apertures t3 provided in said cone. Thesleeve t1 can be adjusted axially to tension the blade against the faceof the work which is indicated at v. The tube d'7 and sleeve t1 arepreferably provided with left-hand threads.

To insert the blade a in the handles, the ring d8 of the left-handhandle is unscrewed from the lining d5, and the sleeve t1 and tube d?can then be removed together. The lining d5 is slightly turned andpushed into the base portion d to expose the left-hand block c and allowone end of the blade to be engaged with the split clamp b thereof andthe holding nut thereon tightened up. The lining d5 is then pulled outto its full extent and turned to lock it against inward movement, andthe sleeve t1 and tube d'1 are replaced and secured by the ring d8.' Tosecure the other end of the blade to the block c in the righthandhandle, the flywheel m, m2 on the motor shaft n is rotated to cause theflexible drive to move the clamp b of said block opposite to aperturest4 and d3 provided in the sleeve t and the portion d1 respectively, thesleeve t being revolved, if necessary, to bring the aperture t4 intoregister with the aperture d3. The holding nut b1 of the clamp can thenbe turned by a small box spanner inserted through said apertures tosecure the right-hand end of the blade therein. The flywheel m, m2 may,if desired, be biassed so that it tends to come to a standstill in sucha position that the clamp b is opposite to the apertures t4 and d3.

The front faces of the apertured cone t2 and the ring u lie in planesperpendicular to the direction in which the blade a reciprocates, andare accurately machined to allow them to be held flat against thesurface of the work 'u on each side thereof as shown in Fig. 4 when thelatter is of such a nature as to permit this. The forward faces of theapertured cone t2 and the ring u ensure that the blade a reciprocates inalignment with the axes of the handles d and that the plane of the cutis perpendicular to said faces. For beveling, the plane of the face ofthe right-hand handle may be 45 to the direction of reciprocation. Wherethe work consists of a thin board supported only at one point (as in abench vise), the application of said faces to the work prevents theboard vibrating during the sawing operation and assists in accuratelyguiding the saw blade.

A foot-operated press switch (not illustrated) is provided in aconvenient position to control the supply of current to the moto-r Whilethe hands of the operator are engaged in guiding the handles d betweenwhich'the blade a. reciprocates.

The positions of the blocks c on the ends of the voperating cables f inrelation to the handles d may be adjusted, when necessary, by adjustingthe stops r1 in the ends of the handles. The spherical-headed nipples hwhereby the flexible cables f are attached to the collars j of thereciprocating mechanism allow the cables to rid themselves of any twistdue to adjustment of the stops r1.

Instead of connecting each end of the saw blade a by a flexible cable fto the reciprocating mechanism and employing a pair of handles d as inthe example illustrated in Figs. l to 4, I may, as illustrated in Figs.5 to l0, employ a rigid blade al' projecting from a single handle d, theend of said blade within said handle being rigidly clamped at bl to ablock cV coacting with a strong spring e and attached at g to one end ofa flexible cable f whose other end is attached at h to a single collar:i on an eccentric pin lc projecting from the face of a flywheel m fixedon the end of the shaft n; of an electric motor o. handled saw, theoperating cable f is enclosed in a flexible non-reciprocating sheath pabutting at one end against an adjustable stop r1 screwed into the rearend of the handle d and at the other end against a fixed stop r2 at oneend of the casing q enclosing the reciprocating mechanism, said sheathbeing enclosed in a flexible tube r supplied with oil from the casing qin similar manner tothe flexible tubes enclosing the drive of thetwo-handled saw. Oil is supplied to the casing q through an apertureclosed by a plug q3 fitted with a dipper rod qf'and a drainage plug q5is also provided.

The tube r is protected near the casing q by a short length of flexibletubing w of heavier make than the tube r and is supported by a iiexibleguard comprising a spring :c one end of which is rigidly heldin a socketx1 attached to the end of the casingq, said spring embracing the tube wAs in the twoalmost to the outerend of the latter and then 'I'hestoppage of the block c does .not therefore -being disengagedfrom-saidtube and bent at an angle at :1:2,fthe other end of the spring beingattached by a bolt x3 to one of the feet o4 of the lmotor. I'he supportgiven by the spring :c and outer tube i'Lo prevents the outer tube beingtoo acutely bent and also prevents undesirable angular movement of theinner tube r and sheath p about the point where the former is attachedto the casing q. A spring clip y is provided on the opposite end of thecasing q to the socket w1 to receive the handle d when the tool is notin use, the flexible drive being loosely coiled around the motor.

The feet o4 of the motor are bolted to a frame comprising a pair ofangularly-disposed tubular members o2 welded together at o3 to form acarrying handle whereby the motor and tool can be readily transported.

The single handle which is illustrated in Figs. 'l to 10 comprises abase portion d closed at its rear end and having at its forward end acylindrical extension d1 formed with the axial slot d2 to receive theprojection s on the block c which prevents relative rotation between theblock and the handle. The end of the saw blade a1 and the end of theoperating cable f are rigidly clamped to the block as in the two-handledarrangement. 'Ihe cylinder d1 is screwed into the forward end of thebase portion d and terminates in a cone t2 provided with inspectionapertures t3. The front edge of said cone lies in a plane perpendicularto the direction in which the blade reciprocates. Over the cylinder d1is slipped a loose sleeve t in which is an aperture t4 which, bypartially revolving the sleeve, can be moved into register with anaperture d3 in the cylinder d1 to permit the insertion of a smallbox`spanner whereby the holding nut b1 of the sp-lit clamp bv can bemanipulated to release or secure the blade w1 to permit of its removaland replacement in case of breakage or when desired. Normally the sleevet is clamped against rotation by screwing up the base portion d on thecylinder d1, but the sleeve can be readily released for rotation whendesired by slightly slackening the joint.

'Ihe motor driving the reciprocating mechanism may be controlled by aswitch or plug in any convenient position, and, to enable the saw bladeto be stopped at will by the person holding the handle without affectingthe running of the motor, I provide a set screw a in the rear end of thecone t2, said screw having a knurled head al for ready rotation. Alocking ring z2 is mounted on a thread on the rear end of the cone, andcan be adjusted to press against the screw e to hold it and prevent itworking loose.

The screw e can be projected into the handle to coact with the inclinedface c1 on the block c therein. When the screw is retracted, the blockand saw reciprocate the full extent of the drive, but, on rotating thescrew to project it into` the handle, it engages the face c1 andprogressively curtails the forward stroke of the block until eventuallythe block is prevented from working from its most rearward position andis therefore held stationary. The connection of the end of the flexiblecable ,f to the collar j on the eccentric pin lc of the reciprocatingmechanism is by means of a spherical-headed nipple h as described inconnection with the double-handled tool of Figs. 1 to 4, and allows thenipple at the end of the cable to revolve freely in its socket in saidcollar when the driving tension is released so that twists imparted tothe cable are removed.

interfere with the running of the motor, and the screw z can be used tohold the block during removal and replacement of the blade a1.

While I have herein described reciprocating mechanism driven by anelectric mo-tor, it will be understood that, if desired, a suitableinternalcombustion engine or compressed air engine may be substitutedfor the electric motor, and while I have illustrated and described handtools tted with saw blades, it will be understood that a le or othercutting tool may be substituted for the saw blade.

Changes of a minor character may be made in the construction andarrangement of the various parts of my improved hand tools withoutdeparting from the essential features and purposes of rmy invention, andit is my intention to cover by my claims any modified forms of structureor use of mechanical equivalents which may be reasonably included withintheir scope.

I declare that what I claim and desire to secure by Letters Patentisz- 1. A power-driven reciprocating hand tool comprising, incombination, a power-driven flywheel, a pin eccentrically mounted onsaid ilywheel, an oiltight casing enclosing said flywheel land eccentricpin, a flexible cable connected to said eccentric pin to transmit thepull thereof in one direction, a sheath around said cable coactingtherewith, means for attaching said sheath to said casing which allowoil therein under pressure due to the centrifugal action of s-aidflywheel to pass continuously from said casing into said sheath, apiston-like block attached at its rear end to the end of said cableremote from said eccentric pin, a cylindrical handle enclosing saidblock concentric with said cable, means for preventing rotation of saidblock in said handle whilst allowing it to slide therein, means forclamping a cutting tool to the forward end of said block, a springinterposed between the rear end of said handle and said block, and meansfor attaching the adjacent end of the sheath to the rear end of saidhandle which means allow the oil in said sheath to pass therefrom intosaid handle.

2. The combination with a power-driven reciprocating hand tool asclaimed in claim 1, of an apertured conical guard support attached tothe forward end of the cylindrical handle, said guard support having afrontal surface to engage the work when manipulating the tool.

3. The combination with a power-driven reciprocating hand tool asclaimed in claim 1, of adjustable means for holding the piston-likeblock stationary in the cylindrical handle.

4. The combination with a power-driven reciprocating hand tool asclaimed in claim 1, of an apertured conical guard support attached tothe forward end of the cylindrical handle, said guard support having afrontal surface to engage the work when manipulating the tool, a setscrew in said guard support, and an inclined face on the piston-11k@mock in the handle with which said set screw coacts to hold said blockstationary.

5. A power-driven reciprocating hand tool comprising, in combination, apower-driven flywheel, a pin eccentrically mounted on said flywheel, anoiltight casing enclosing said flywheel and eccentric pin, a pair offlexible cables oppositely connected to said eccentric pin, sheathsaround said cables coacting therewith to trans'- mit the reciprocatorymotion of said eccentric pin, means for attaching said sheaths to saidcasing which allow oil therein under pressure due vto the centrifugalaction of said iiywheel to pass Continuously from said casing into saidsheaths, a piston-like block attached at its rear end to the end of eachof said cables remote from said eccentric pin, a cylindrical handleenclosing each block concentric with its cable, means for preventingrotation of the block in one of said handles whilst allowing it to sidetherein, means for clamping the ends of a cutting tool tol the forwardends of said blocks, springs interposed between the rear ends of saidhandles andthe blocks therewithin, and means for attaching the adjacentends o-f the sheaths to the rear ends of said handles which means allowthe oil in said sheaths to pass therefrom into said handles.

WILLIAM HENRY DEAN.

